Terms/eras I've heard used now and again in the discussion of mad inventor scientist-fiction:

Lone Inventor - Frankenstein, Jekyll, Moreau, etc.
Industrial Threats - Usually mass-produced threats to decency and world order as we know it...Often used with relation to late 19th c. and early 20th c. mass production of rifles, automatic weapons, flamethrowers and similar things.
Big Machine - The Bomb, giant robots, giant broadcasting ray stations (The Master), generally some single thing built by a mad inventor with an industrial backing which threatens the world/society/etc.

If you haven't read White's juvenile 'The Master', it's something of a classic of the Big Machine era. The title character has the island base full of strange machines, is described with a Victorian inhumanness I have only seen equalled by Conan-Doyle discussing some of his more terrible villains. Terribly emotionless and inscrutable, deep-sunken piercing eyes, a tremendously high forehead and a skull whose face seems to have shrunken in to better expose the arch of the cranium behind it. Almost immobile, one arm swinging out with implacable mechanical smoothness to pick up a book or a tumbler of whiskey...the body seeming to exist purely to support the brain. And that's just what I remember off the top of my head. Quite the character for a 40s-50s era juvenile.

Huh. I hadn’t encountered those categorizations before. The notes do more or less recapitulate them, albeit in a roundabout way. Nor had I heard of The Master, which indeed sounds vivid and intense for a juvenile, particularly of that era.